1. Field of the Invention
The present invention relates to a laminated inductor and more particularly, the present invention relates to a laminated inductor for use as a noise filter or other component in, for example, various electronic circuits and apparatuses.
2. Description of the Related Art
Up to now, among such laminated inductors, an inductor in which a coil 50 is disposed inside of a laminated body by connecting spiral coil conductor patterns 51 and 52 in regular order through via holes 53 as shown in FIG. 6 is known. The coil 50 is composed of the coil conductor patterns 51 and 52, each of which constitutes two turns, and the via holes 53. That is, the coil 50 is constructed such that the coil conductor pattern 51 extending in a spiral direction from the outside to the inside and the coil conductor pattern 52 extending in a spiral direction from the inside to the outside are alternately disposed. In this way, the conventional spiral coil conductor patterns 51 and 52 have the same number of turns (two or more turns) and are alternately connected in series, and consequently, a high inductance was obtained in a small-sized inductor.
However, in the laminated inductor using the conventional spiral coil conductor patterns, since the coil conductor patterns 51 and 52 having a multiple number of turns (two or more turns) are used, the inductance of each turn cannot be adjusted, and accordingly, there was a problem in that the center value of conductance of each turn cannot be matched to each other.
Furthermore, in the conventional laminated inductor, when a necessary inductance cannot be obtained, such countermeasures as the use of coil conductor patterns having many turns, and the use of a material having a high permeability as a laminated body, were taken. However, when the number of turns is increased in the coil conductor patterns 51 and 52, it is necessary to reduce the pattern width of the coil conductor patterns 51 and 52. As a result, there was a problem in that the direct-current resistance of the coil 50 increases. Furthermore, when a material having a high permeability is used as a laminated body, the magnetic saturation occurs in the laminated inductor, and there was a problem in that the direct-current superposition characteristics deteriorate.
In this way, since the number of turns of the coil conductor pattern is restricted in the conventional laminated inductor, there was a problem in that the degree of freedom of design is low and that it is difficult to obtain the most appropriate characteristics.